In the oil and gas industry, core samples taken from oil and gas reservoirs are commonly analyzed to determine or measure various characteristics of the reservoir. Such analysis may include viewing thin sections of the core samples under a microscope. To enable core samples of unconsolidated reservoir sands to be sliced for thin section analysis, such core samples are typically impregnated with epoxy resin. Known methods for impregnating such sands with epoxy resin, however, are problematic when the sands have relatively low permeability, as typically seen with tight gas sands. The low permeability of the sample results in restricted flow of the epoxy resin-former, such that the epoxy fails to penetrate the entire sample or to flow from one sample to another in a stack of samples being prepared. Improved methods are needed for impregnating low permeability sands with epoxy.